Transmitter for high-frequency sound signaling



July 24, 1928. 1,678,182

M. s. ESTES TRANSMITTER FOR HIGH FREQUENCY SOUND SIGNALING Filed Nov. 25, 1919 //7[/P/7f0/ Harlan 5. fs/es.

Patented July 24, 1928.

MARION S. ESTES, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN EIIEOTRIC COMPANY,

INCORPORATED, 012' NEW YORK N. Y., A CORPORATION OF NEW YORK.

TRANSMITTER son nmn-rnnounncy scrim srormnmq.

Application filed November--25, 1919. Serial No. 340,555.

This invention relates to transmitters for high frequency sound signaling. More particularly, it relates to a device of the condenser transmitter type for use in submarme signaling.

An object of the invention is to provide a high frequency sound transmitter.

Another object of the invention is to provide means for converting the energy of high frequency electrical waves into that of sound waves of corresponding frequency.

provide means for causing electrical Waves of large amplitude to set up sound waves of corresponding amplitude and wave form.

A further object of the. invention is-to' provide a condenser transmitter capable of acting directly upon water or other sound transmitting media to set up ,sound waves therein.

A still further object of the invention 15 to provide a high frequency sound wave transmitter which will bedirective 1n its effect so that the high frequency sound waves will be propagated as a beam.

According to the present invention, acon denser of rugged type 'is so constructed that it ma be immersed in water and maintained polarized to a high potential whlle 1mmersed. One conducting plate of the condenser is made thin and is either exposed to the water or separated therefrom by a thin flexible sheet of dielectric material, and upon application of ,electrical oscillations to the condenser, this plate is'acted upon by electrostatic attraction so that it vibrates and sets up correspondin soundwaves in the water immediately a jacent to its surface. These sound waves, which are preferably of high frequency, are transmitted through the water and are received and detected by suitable receiving means.

Referring to the drawing, Fig. 1 1llustrates diagrammatically a- .circuit arrangement in which-this invention may be employed; transmltte or vibrator; F ig. 3- a section on line3 3 of Fig. 2; and Fig. 4 a. similar section of a modified form of vibrator. I

"As shown in Fig. 1, a source -1 of alter? nating current is connected in circuit with thecondensertransmitter 2 through alarge capacity blocking condenser 3. A switch 4 serves towconnect in serieswith the circuit either akey 5 or amicrophone 6. A. source transmitter. -ber 19 is attached to casing 9 and an insug.-2 isa plan view of a'condenser 7 of unidirectional current is also connected i to the terminals of condenser transmitter 2 to polarize it. A high'frequency retard coil 8 serves to exclude the current produced by source 1 from the path including source 7. Blocking condenser 3 prevents flow of unidirectional current through the path including source 1.

The structure of one form of a condenser transmitter according to this invention is illustrated in Figs. 2 and 3. A heavy annu- A further object-of the invention is tolar metallic casing or base member 9 has outrated therefrom by insulating casing 13 is a conducting plate 14. A thin circular conducting plate 15 covers the exposed face of conducting plate 14 and isinsulated therefrom by interposed dielectric material 16.

An annular clamping ring 17, preferably of conducting material, secured to casing 9 by bolts 18, serves to hold the parts in position. Conductingplates 14 and 15 with interposed dielectric material 16 constitute a condenser A conducting terminal memlation covered terminal conductor 20 passing through an insulating .bushing 21 in casing 9 is electrically connected to plate 14. Ring 17 is electrically connected to casing 9 in any suitable manner as,. for example, by

bolts 18. Thejoint between the casing 9. and

the conducting plate 15 may be sealedin any desired manner to make 1t fluid-tight. It has been found that a suitable joint may be secured by applying valve rease to the parts at the joint and by heating the transmitter during assembly to melt the grease. Plate 14 is thus effectively insulated from casin 9, conducting plate 15' and the sur-- roun 'ng medium.

In Fig. 4 is shown denser transmitter having a flat back plate or base member 22, a clamping ring 23 attached to the casing by means of bolts 24 and a multiple-lcaved "condenser element" clamped between the plate 22 and ring 23. The condenser element consists of a series of conducting plates 25 alternately interposed with another series of conducting lates 26. A sheet of insulating material 2 preferably very thin, covers the outer face of -outer a modified form of conplate 25 and dielectric material is placed between each two adjacent plates of the con- 30 passes, and these apertures'are of such size as to prevent electrical contact between these plates and the conductor. If desired, annular washers of insulatin material of the same thickness as the conducting plates may be placed in the apertures. A conductor 29 is connected to the back plate 22 and plates 26 are electrically connected to the back plate by any suitable means such as bolts 24.

Although various dimensions may be given the parts of the transmitter, in one example actually used, the outer conductmg plate of the condenser was approximately eight inches in diameter with thin leaves of mica for dielectric. This condenser had a capacity of 57 x 10- farads when polarized to the conductors 19 and 20, to which the polarizing source may also be connected,

the electrostatic action will cause a motion of the outer conducting platev which is transferred as a corresponding sound wave to the adjacent medium. When the switch 4 of Fig. 1 is thrown to the upper position,

key 5 may be used to interrupt the high frequency waves for telegraph or other impulse signaling. When thrown to the opposite position, microphone 6 may be used to vary the amplitude of the high frequency waves in well known manner for the transmission of speech or other sounds. In the modification shown in Figs. '2 and 3, the outer conducting plate is directly in contact wlth the adjacent medium, but in the modification of Fig. 4:, the Outer conducting plate imparts its motion to-insulation sheet 27, which is preferably thin mica, and this sheet in turn transmits the motion to the adjacent medium as a sound wave.

The surface from whicli'motion is transmitted to the adjacent medium, that is, the surface of the outer conducting plate or the thin dielectric sheet covering it, as the case may be. is of large, area and accordingly the transmission of sound by this apparatus is highly directive. The supporting member 12 may be used to position the plane of the sound transmitting member-exactly with reference to any desired receiving point. found that with the transmitting vibrator 8 inches in diameter, at a frequency of 75,000

cycles per second, and at a'distance of 2,000

feet between transmitter and receiver, it is possible to determine the direction of the transmitter within one degree, and the sound is practically lost at the receiving station if the transmitteris turned five degrees from the direction of correct pointing. It is, therefore, possible to select any of a number of signaling stations to the exclusion of the others, provided the angular difference of their directions from the transmitting point is not too small.

The device is simple and rugged, both electrically and mechanically, as is required in submarine signaling with 'high polarizing voltage. The type of deviceillustrated in Fig.4.- permits any desired capacity to be obtained.

It is to be understood that this invention is not to be limited to the details shown and that the. circuit of Fig. 1 is merely a. diagram of a conventional circuit in which the novel transmitter may be employed. Although the transmitter has been described in connection with submarine signaling, it is obviously capable of use in any sound transmitting medium and in the transmitting and selecting-of other controlling impulses of any wave form and frequency, as well as for signal transmission.

What is claimed is:

1. A transmitter of superaudible frequency waves comprising a rigid base memher, an elastlc condenser plate havln a mass which is small as compared with t at, of the base member, a second condenser plate, meanssubstantially rigidly connecting said second condenser plate, to said base member, means for electrically connecting said first plate with said base member and said other )late, and means hermetically covering bot of said condenser plates, comprising an insulating sheet having asmall mass as compared with that of either of said plates and arranged relatively to said first plate so that the motion of said first late is transmitted therethrough to the me ium.

2. A condenser transmitter comprising condenser plates of opposite polarity, a conductive base member supporting said plates, an electrical connection between one of said making electrical connection with each of said plates.

3. A condenser transmitter comprismg a conductive base member, a thin flexible sheet As a practical example, it has been plates and said base member, solid insulatsulated from said member, and means for of dielectric material joined to said base member, a condenser plate interposed be tween said sheet and said member and inrendering fluid-tight the joint between said sheet and said member.

4. A condenser transmitter comprising a base member, aplurality of conducting plates mounted thereon, means electrically connecting said conducting plates, 'a-plurality of conducting plates interposed beinsulated therefrom, said base member being massive as compared with each of said plates and said interposed plates and said ase member being apertured, and a conducting member passin throu h said apertures and connected on y to said interposed 4 plates.

In witness whereof, I hereunto subscribe 20 naygname this 19th day ofNovember, A. D.

tween said electrically connected plates and MARION s. ESTES:- 

